Image reading device and image forming device for detecting presence of dust on a reading position

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2014-233910 filed Nov. 18, 2014.

BACKGROUND

Technical Field

The present invention relates to an image reading device and an image forming device.

SUMMARY

According to an aspect of the present invention, there is provided an image reading device including: a transport path through which a document is transported; a reading member that reads an image of the document at a reading position set in advance on the transport path, the reading member including a light source that is movable with respect to the reading position in a sub scanning direction which extends along a document transport direction and being capable of reading at plural positions in the sub scanning direction; a reflecting member that has a reflecting surface that faces the reading member over a range that includes the reading position and that extends to a position that is different from the reading position in the sub scanning direction, a difference between an amount of light reflected from the reflecting surface and an amount of light reflected from the document being set to be larger than a difference in amount of light set in advance; a movement controller that controls the reading member so as to move the light source with respect to the reading position before the document is transported to the reading position in a case where the reading member reads the image of the document; a dust determination unit that determines presence of dust on a basis of an image read when the light source is moved; and an announcement member that announces presence of dust to a user in a case where it is determined that dust is present.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the present invention will be described in detail based on the following figures, wherein:

<figref idref="DRAWINGS">FIG. 1</figref> is an overall view of an image forming device according to a first exemplary embodiment;

<figref idref="DRAWINGS">FIG. 2</figref> is an enlarged view of a visible image forming device according to the first exemplary embodiment;

<figref idref="DRAWINGS">FIG. 3</figref> is an overall view of an image reading device according to the first exemplary embodiment;

<figref idref="DRAWINGS">FIG. 4</figref> illustrates a portion of a body portion of the image reading device according to the first exemplary embodiment;

<figref idref="DRAWINGS">FIG. 5</figref> is a block diagram illustrating the functions of a control section of the image forming device according to the first exemplary embodiment;

<figref idref="DRAWINGS">FIG. 6</figref> illustrates an announcement screen according to the first exemplary embodiment;

<figref idref="DRAWINGS">FIG. 7</figref> is a flowchart illustrating an image reading process according to the first exemplary embodiment;

<figref idref="DRAWINGS">FIG. 8A</figref> is a graph illustrating a detected value of reflected light detected by a solid-state imaging device without the presence of dust to illustrate the effect of the first exemplary embodiment, in which the vertical axis represents the tone value and the horizontal axis represents the main scanning direction; and

<figref idref="DRAWINGS">FIG. 8B</figref> is a graph illustrating a detected value of reflected light detected by the solid-state imaging device with the presence of dust to illustrate the effect of the first exemplary embodiment, in which the vertical axis represents the tone value and the horizontal axis represents the main scanning direction.

DETAILED DESCRIPTION

A specific exemplary embodiment (hereinafter referred to as an “exemplary embodiment”) of the present invention will be described below with reference to the drawings. The present invention is not limited to the following exemplary embodiment.

In the drawings, in order to facilitate understanding of the following description, the front-rear direction is defined as the X-axis direction, the left-right direction is defined as the Y-axis direction, and the up-down direction is defined as Z-axis direction, and the directions and the sides indicated by the arrows X, −X, Y, −Y, Z, and −Z are referred to as forward, rearward, rightward, leftward, upward, and downward, and the front side, the rear side, the right side, the left side, the upper side, and the lower side.

In the drawings, in addition, a circular mark provided with a dot in the center means an arrow directed from the back side toward the front side of the drawing sheet surface, and a circular mark provided with a cross mark in the center means an arrow directed from the front side toward the back side of the drawing sheet surface.

In the following description of the drawings, members other than those required to facilitate understanding the description are not illustrated as appropriate.

[First Exemplary Embodiment]

<figref idref="DRAWINGS">FIG. 1</figref> is an overall view of an image forming device according to a first exemplary embodiment.

<figref idref="DRAWINGS">FIG. 2</figref> is an enlarged view of a visible image forming device according to the first exemplary embodiment.

As illustrated in <figref idref="DRAWINGS">FIG. 1</figref>, a copier U that serves as an example of the image forming device includes an operation section UI, a scanner section U<b>1</b> that serves as an example of an image reading device, a feeder section U<b>2</b> that serves as an example of a medium supply device, an image preparation section U<b>3</b> that serves as an example of an image recording device, and a medium processing device U<b>4</b>.

(Operation Section UI)

The operation section UI includes input buttons UIa used to start copying, set the number of copies to be made, and so forth. The operation section UI also includes a display section UIb that displays a content input using the input buttons UIa and the state of the copier U.

(Scanner Section U<b>1</b>)

<figref idref="DRAWINGS">FIG. 3</figref> is an overall view of the image reading device according to the first exemplary embodiment.

As illustrated in <figref idref="DRAWINGS">FIGS. 1 and 3</figref>, the scanner section U<b>1</b> includes a scanner body U<b>1</b><i>b </i>that serves as an example of the body portion of the image reading device. The scanner body U<b>1</b><i>b </i>includes a document platen PG that is transparent and provided at the upper end of the scanner body U<b>1</b><i>b</i>. A document transport device U<b>1</b><i>a </i>is supported on the upper surface of the scanner body U<b>1</b><i>b </i>so as to open and close the document platen PG.

The document transport device U<b>1</b><i>a </i>includes a document feed tray U<b>1</b><i>a</i><b>1</b> that serves as an example of a document loading portion. Plural documents Gi to be copied are housed in a stacked state in the document feed tray U<b>1</b><i>a</i><b>1</b>. A document transport portion U<b>1</b><i>a</i><b>2</b> is provided to the left of the document feed tray U<b>1</b><i>a</i><b>1</b>. The document transport portion U<b>1</b><i>a</i><b>2</b> transports the document G<b>1</b> in the document feed tray U<b>1</b><i>a</i><b>1</b> onto the document platen PG. A document paper exit tray U<b>1</b><i>a</i><b>3</b> that serves as an example of a document ejection portion is disposed under the document feed tray U<b>1</b><i>a</i><b>1</b>. The document Gi having passed through the document platen PG is ejected from the document transport portion U<b>1</b><i>a</i><b>2</b> to the document paper exit tray U<b>1</b><i>a</i><b>3</b>.

As illustrated in <figref idref="DRAWINGS">FIG. 3</figref>, a document passage surface PG<b>1</b> that serves as an example of a first reading surface is disposed at the left end portion of the document platen PG in correspondence with a first image reading position P<b>1</b> set in advance. The document Gi transported by the document transport device U<b>1</b><i>a </i>passes through the document passage surface PG<b>1</b>. A document placement surface PG<b>2</b> that supports the document G<b>1</b> placed by a user is disposed to the right of the document passage surface PG<b>1</b>. A document guide PG<b>3</b> that serves as an example of a guide section is supported between the document passage surface PG<b>1</b> and the document placement surface PG<b>2</b>. The document guide PG<b>3</b> guides the document G<b>1</b> having passed through the document passage surface PG<b>1</b> into the document transport device U<b>1</b><i>a. </i>

A light-exposure optical system A is supported inside the scanner body U<b>1</b><i>b</i>. The light-exposure optical system A includes a lamp La that serves as an example of a light source. The lamp La radiates light toward the document G<b>1</b> passing on the document passage surface PG<b>1</b> or the document Gi placed on the document placement surface PG<b>2</b>. Reflected light from the document Gi is converted into an electrical signal for red R, green G, and blue B by a solid-state imaging device CCD that serves as an example of a first reading member via plural optical members of the light-exposure optical system A, and the electrical signal is input to an image processing section GS.

The image processing section GS converts the electrical signal for R, G, and B input from the solid-state imaging device CCD into image information for black K, yellow Y, magenta M, and cyan C, temporarily stores the image information, and outputs the image information to a drive circuit D of a latent image forming device of the image preparation section U<b>3</b> as image information for latent image formation at a timing set in advance.

In the case where a document image is a so-called monochrome image, image information for black K only is input to the drive circuit D of the latent image forming device.

The scanner body U<b>1</b><i>b </i>according to the first exemplary embodiment is composed of the document platen PG, the light-exposure optical system A, the solid-state imaging device CCD, and the image processing section GS.

(Feeder Section U<b>2</b>)

As illustrated in <figref idref="DRAWINGS">FIG. 1</figref>, the feeder section U<b>2</b> includes plural paper feed trays TR<b>1</b>, TR<b>2</b>, TR<b>3</b>, and TR<b>4</b> that serve as examples of medium storage containers. The feeder section U<b>2</b> also has a medium supply path SH<b>1</b> etc. Recording paper S that serves as an example of an image recording medium and that has been taken out of the paper feed trays TR<b>1</b> to TR<b>4</b> is transported to the image preparation section U<b>3</b> through the medium supply path SH<b>1</b>.

(Image Preparation Section U<b>3</b> and Medium Processing Device U<b>4</b>)

As illustrated in <figref idref="DRAWINGS">FIG. 1</figref>, the image preparation section U<b>3</b> includes an image recording section U<b>3</b><i>a </i>that records an image on the recording paper S transported from the feeder section U<b>2</b> on the basis of the document image read by the scanner section U<b>1</b>.

As illustrated in <figref idref="DRAWINGS">FIGS. 1 and 2</figref>, the drive circuit D of the latent image forming device of the image preparation section U<b>3</b> outputs a drive signal to latent image forming devices ROSy, ROSm, ROSc, and ROSk for the colors Y to K on the basis of the image information input from the scanner section U<b>1</b> at a timing set in advance. Photosensitive drums Py, Pm, Pc, and Pk that serve as examples of image holding elements are disposed under the latent image forming devices ROSy to ROSk, respectively. The rotating surfaces of the photosensitive drums Py, Pm, Pc, and Pk are uniformly charged by charging rollers CRy, CRm, CRc, and CRk, respectively, that serve as examples of chargers. An electrostatic latent image is formed on the charged surfaces of the photosensitive drums Py to Pk by laser beams Ly, Lm, Lc, and Lk, respectively, that serve as examples of latent image writing light output from the latent image forming devices ROSy, ROSm, ROSc, and ROSk. The electrostatic latent images on the surfaces of the photosensitive drums Py, Pm, Pc, and Pk are developed into toner images that serve as examples of visible images for yellow Y, magenta M, cyan C, and black K, respectively, by developing devices Gy, Gm, Gc, and Gk.

A developer consumed for development in the developing devices Gy to Gk is replenished by toner cartridges Ky, Km, Kc, and Kk that serve as examples of developer storage containers removably mounted to a developer replenishment device U<b>3</b><i>b</i>. In the first exemplary embodiment, a two-part developer containing a toner and a carrier is used as the developer. A so-called highly concentrated developer containing a larger proportion of toner than the concentration of toner in the developing devices Gy to Gk is supplied from the toner cartridges Ky, Km, Kc, and Kk. Thus, in the developing devices Gy to Gk according to the first exemplary embodiment, the carrier is exchanged by discharging a developer containing a degraded carrier little by little from the developing devices Gy to Gk while supplying a highly concentrated developer containing a small amount of carrier. Such a technique for exchanging a carrier little by little is known in the art, and therefore is not described in detail.

In the developing devices Gy to Gk, the developer in the developing devices Gy to Gk is exchanged with a new developer little by little by discharging the developer containing a degraded carrier to the rear end portion of the developing devices Gy to Gk from degraded developer discharge portions G<b>1</b><i>y </i>to G<b>1</b><i>k </i>and supplying a developer containing a new carrier from the toner cartridges Ky to Kk. The developer discharged from the degraded developer discharge portions G<b>1</b><i>y </i>to G<b>1</b><i>k </i>flows into degraded developer transport paths G<b>2</b><i>y </i>to G<b>2</b><i>k </i>that extend rearward, and is transported rearward by degraded developer transport members G<b>3</b><i>y </i>to G<b>3</b><i>k </i>disposed in the degraded developer transport paths G<b>2</b><i>y </i>to G<b>2</b><i>k </i>to be collected by a degraded developer collection portion (not illustrated).

The toner images on the surfaces of the photosensitive drums Py, Pm, Pc, and Pk are transferred onto an intermediate transfer belt B that serves as an example of an intermediate transfer body by first transfer rollers T<b>1</b><i>y</i>, T<b>1</b><i>m</i>, T<b>1</b><i>c</i>, and T<b>1</b><i>k</i>, respectively, that serve as examples of first transferers sequentially in first transfer regions Q<b>3</b><i>y</i>, Q<b>3</b><i>m</i>, Q<b>3</b><i>c</i>, and Q<b>3</b><i>k </i>in an overlapping manner to form a color toner image that serves as an example of a multi-color visible image on the intermediate transfer belt B. The color toner image formed on the intermediate transfer belt B is transported to a second transfer region Q<b>4</b>.

In the case of image information for K color only, only the photosensitive drum Pk and the developing device Gk for K color are used to form only a toner image for K color.

Drum cleaners CLy, CLm, CLc, and CLk that serve as examples of image holding element cleaners are used to remove residues such as a residual developer and paper powder that adhere to the surfaces of the photosensitive drums Py, Pm, Pc, and Pk after the first transfer.

In the first exemplary embodiment, the photosensitive drum Pk, the charging roller CRk, and the drum cleaner CLk are integrated as a photosensitive unit UK for K color that serves as an example an image holding element unit. Also for the other colors Y, M, and C, photosensitive units UY, UM, and UC are composed of the photosensitive drums Py, Pm, and Pc, the charging rollers CRy, CRm, CRc, and the drum cleaners CLy, CLm, and CLc, respectively.

In addition, a visible image forming device UK+Gk for K color is composed of the photosensitive unit UK for K color and the developing device Gk having a developing roller R<b>0</b><i>k </i>that serves as an example of a developer holding element. Likewise, visible image forming devices UY+Gy, UM+Gm, and UC+Gc for Y, M, and C colors are composed of the photosensitive units UY, UM, and UC for Y, M, and C colors and the developing devices Gy, Gm, and Gc having developing rollers R<b>0</b><i>y</i>, R<b>0</b><i>m</i>, and R<b>0</b><i>c</i>, respectively.

A visible image forming device drawer U<b>3</b><i>c </i>that serves as an example of a drawing member is disposed under the latent image forming devices ROSy, ROSm, ROSc, and ROSk for the colors Y to K. The visible image forming device drawer U<b>3</b><i>c </i>is supported by slide rails R<b>1</b>, R<b>1</b> that serve as an example of a pair or left and right guide members so as to be movable between a drawn position at which the visible image forming device drawer U<b>3</b><i>c </i>is drawn forward of the image preparation section U<b>3</b> and a mounted position at which the visible image forming device drawer U<b>3</b><i>c </i>is mounted inside the image preparation section U<b>3</b>.

The visible image forming device drawer U<b>3</b><i>c </i>includes a drawer body U<b>3</b><i>c</i><b>1</b> that serves as an example of a holding portion. The photosensitive units UY, UM, UC, and UK and the developing devices Gy, Gm, Gc, and Gk are removably mounted to the drawer body U<b>3</b><i>c</i><b>1</b>.

An intermediate transfer device drawer U<b>3</b><i>d </i>that serves as an example of a drawing member is disposed under the visible image forming device drawer U<b>3</b><i>c</i>. The intermediate transfer device drawer U<b>3</b><i>d </i>is supported so as to be movable between a drawn position at which the intermediate transfer device drawer U<b>3</b><i>d </i>is drawn forward of the image preparation section U<b>3</b> and a mounted position at which the intermediate transfer device drawer U<b>3</b><i>d </i>is mounted inside the image preparation section U<b>3</b>. A belt module BM that serves as an example of an intermediate transfer device is supported by the intermediate transfer device drawer U<b>3</b><i>d </i>so as to be ascended and descended between an ascended position at which the belt module BM contacts the lower surfaces of the photosensitive drums Py, Pm, Pc, and Pk and a descended position at which the belt module BM is separated downward from the lower surfaces of the photosensitive drums Py, Pm, Pc, and Pk.

The belt module BM includes the intermediate transfer belt B, a drive roller Rd that serves as an example of an intermediate transfer body drive member, a tension roller Rt that serves as an example of a tension application member, a walking roller Rw that serves as an example of a meandering prevention member, plural idler rollers Rf that serve as examples of driven members, a back-up roller T<b>2</b><i>a </i>that serves as an example of an opposing member, and the first transfer rollers T<b>1</b><i>y</i>, T<b>1</b><i>m</i>, T<b>1</b><i>c</i>, and T<b>1</b><i>k</i>. Belt support rollers Rd+Rt+Rw+Rf+T<b>2</b><i>a </i>that serve as an example of an intermediate transfer member support member are composed of the drive roller Rd, the tension roller Rt, the walking roller Rw, the idler rollers Rf, and the back-up roller T<b>2</b><i>a</i>. The intermediate transfer belt B is supported by the belt support rollers Rd+Rt+Rw+Rf+T<b>2</b><i>a </i>so as to be rotatable in the direction of the arrow Ya.

A second transfer unit Ut is disposed under the back-up roller T<b>2</b><i>a</i>. The second transfer unit Ut includes a second transfer roller T<b>2</b><i>b </i>that serves as an example of a second transfer member. The second transfer roller T<b>2</b><i>b </i>is disposed so as to be brought into and out of press contact with the back-up roller T<b>2</b><i>a </i>across the intermediate transfer belt B. The second transfer region Q<b>4</b> is formed by a region in which the second transfer roller T<b>2</b><i>b </i>contacts the intermediate transfer belt B. In addition, a contact roller T<b>2</b><i>c </i>that serves as an example of a power feed member contacts the back-up roller T<b>2</b><i>a</i>. A second transfer voltage having the same polarity as the toner charging polarity is applied from a power source circuit E controlled by a control section C to the contact roller T<b>2</b><i>c </i>at a timing set in advance.

A second transferer T<b>2</b> is composed of the back-up roller T<b>2</b><i>a</i>, the second transfer roller T<b>2</b><i>b</i>, and the contact roller T<b>2</b><i>c. </i>

A medium transport path SH<b>2</b> is disposed under the belt module BM. The recording paper S fed from the supply path SH<b>1</b> of the feeder section U<b>2</b> is transported to a resister roller Rr that serves as an example of a transport timing adjustment member by a transport roller Ra that serves as an example of a medium transport member. The resister roller Rr transports the recording paper S downstream at a timing that matches the transport of the toner image formed on the intermediate transfer belt B to the second transfer region Q<b>4</b>. The recording paper S fed by the resister roller Rr is guided by a register-side paper guide SGr and a pre-transfer paper guide SG<b>1</b> to be transported to the second transfer region Q<b>4</b>.

The register-side paper guide SGr according to the first exemplary embodiment is fixed to the image preparation section U<b>3</b> together with the resister roller Rr.

The toner image on the intermediate transfer belt B is transferred to the recording paper S by the second transferer T<b>2</b> when the toner image passes through the second transfer region Q<b>4</b>. In the case of a color toner image, toner images transferred to the surface of the intermediate transfer belt B in an overlapping manner through a first transfer are collectively transferred to the recording paper S through a second transfer.

A transfer device T<b>1</b><i>y </i>to T<b>1</b><i>k</i>+T<b>2</b>+B according to the first exemplary embodiment is composed of the first transfer rollers T<b>1</b><i>y </i>to T<b>1</b><i>k</i>, the second transferer T<b>2</b>, and the intermediate transfer belt B.

The intermediate transfer belt B after the second transfer is cleaned by a belt cleaner CLB that serves as an example of an intermediate transfer body cleaner and that is disposed downstream of the second transfer region Q<b>4</b>. The belt cleaner CLB removes residues such as an untransferred remaining developer and paper powder from the intermediate transfer belt B in the second transfer region Q<b>4</b>. As illustrated in <figref idref="DRAWINGS">FIG. 2</figref>, the residues removed from the intermediate transfer belt B flow into a belt cleaner residue transport path CLB<b>1</b> provided in the lower portion in the belt cleaner CLB to extend rearward, and is transported to the rear side of the image preparation section U<b>3</b> by a belt cleaner residue transport member CLB<b>2</b> disposed in the belt cleaner residue transport path CLB<b>1</b> to be collected by the degraded developer collection portion (not illustrated).

The recording paper S to which the toner image has been transferred is guided by a post-transfer paper guide SG<b>2</b> to be fed to a medium transport belt BH that serves as an example of a transport member. The medium transport belt BH transports the recording paper S to a fixing device F.

The fixing device F includes a heating roller Fh that serves as an example of a heating member and a pressurizing roller Fp that serves as an example of a pressurizing member. The recording paper S is transported to a fixing region Q<b>5</b> which is a region in which the heating roller Fh and the pressurizing roller Fp contact each other. The toner image on the recording paper S is heated and pressurized by the fixing device F to be fixed when the recording paper S passes through the fixing region Q<b>5</b>.

The image recording section U<b>3</b><i>a </i>according to the first exemplary embodiment is composed of the visible image forming devices UY+Gy to UK+Gk, the transfer devices T<b>1</b><i>y </i>to T<b>1</b><i>k</i>+T<b>2</b>+B, and the fixing device F.

A switching gate GT<b>1</b> that serves as an example of a switching member is provided downstream of the fixing device F. The switching gate GT<b>1</b> selectively switches the recording paper S having passed through the fixing region Q<b>5</b> to an ejection path SH<b>3</b> on the medium processing device U<b>4</b> side or a reversal path SH<b>4</b>. The paper S transported to the ejection path SH<b>3</b> is transported to a sheet transport path SH<b>5</b> of the medium processing device U<b>4</b>. A curl correction member U<b>4</b><i>a </i>that serves as an example of a warp correction member is disposed in the sheet transport path SH<b>5</b>. The curl correction member U<b>4</b><i>a </i>corrects a warp, or a so-called curl, of the recording paper S being transported. The recording paper S, a curl of which has been corrected, is ejected with an image fixation surface of the paper facing upward to an ejection tray TH<b>1</b> that serves as an example of a medium ejection portion by an ejection roller Rh that serves as an example of a medium ejection member.

The recording paper S transported to the side of the paper reversal path SH<b>4</b> of the image preparation section U<b>3</b> by the switching gate GT<b>1</b> is transported to the reversal path SH<b>4</b> of the image preparation section U<b>3</b> through a second gate GT<b>2</b> that serves as an example of a switching member.

At this time, in the case where the recording paper S is to be ejected with the image fixation surface facing downward, the transport direction of the recording paper S is reversed after the rear end of the recording paper S in the transport direction passes through the second gate GT<b>2</b>. The second gate GT<b>2</b> according to the first exemplary embodiment is constituted of a thin-film elastic member. Thus, the second gate GT<b>2</b> allows the recording paper S transported to the reversal path SH<b>4</b> to temporarily pass therethrough, and guides the recording paper S toward the transport paths SH<b>3</b> and SH<b>5</b> when the recording paper S having passed therethrough is reversed or switched back. Then, the recording paper S which has been switched back passes through the curl correction member U<b>4</b><i>a</i>, and is ejected to the ejection tray TH<b>1</b> with the image fixation surface facing downward.

A circulation path SH<b>6</b> is connected to the reversal path SH<b>4</b> of the image preparation section U<b>3</b>. A third gate GT<b>3</b> that serves as an example of a switching member is disposed at the portion of connection. In addition, the downstream end of the reversal path SH<b>4</b> is connected to a reversal path SH<b>7</b> of the medium processing device U<b>4</b>.

The recording paper S transported to the reversal path SH<b>4</b> through the switching gate GT<b>1</b> is transported toward the reversal path SH<b>7</b> of the medium processing device U<b>4</b> by the third gate GT<b>3</b>. As with the second gate GT<b>2</b>, the third gate GT<b>3</b> according to the first exemplary embodiment is constituted of a thin-film elastic member. Thus, the third gate GT<b>3</b> allows the recording paper S transported through the reversal path SH<b>4</b> to temporarily pass therethrough, and guides the recording paper S toward the circulation path SH<b>6</b> when the recording paper S having passed therethrough is switched back.

The recording paper S transported to the circulation path SH<b>6</b> is refed to the fixing region Q<b>4</b> through the paper feed path SH<b>1</b> for printing on the second surface.

A sheet transport path SH is composed of elements indicated by the symbols SH<b>1</b> to SH<b>7</b>. In addition, a paper transport device SU according to the first exemplary embodiment is composed of elements indicated by the symbols SH, Ra, Rr, Rh, SGr, SG<b>1</b>, SG<b>2</b>, BH, and GT<b>1</b> to GT<b>3</b>.

(Body Portion U<b>1</b><i>b </i>of Image Reading Device)

<figref idref="DRAWINGS">FIG. 4</figref> illustrates a portion of a body portion of the image reading device according to the first exemplary embodiment.

As illustrated in <figref idref="DRAWINGS">FIGS. 3 and 4</figref>, a glass support port <b>1</b> that serves as an example of an opening is formed in the upper surface of the scanner body U<b>1</b><i>b</i>. The glass support port <b>1</b> according to the first exemplary embodiment is formed in a rectangular shape. A guide support portion <b>2</b> that serves as an example of a partitioning portion is provided on the left portion of the glass support port <b>1</b>. The guide support portion <b>2</b> is formed in the shape of a plate that extends in the front-rear direction.

Hence, the glass support port <b>1</b> is partitioned into a rectangular automatic reading port <b>1</b><i>a </i>on the left end side that extends in the front-rear direction and a rectangular manual reading port <b>1</b><i>b </i>on the right side that is larger than the maximum readable document size set in advance. The document passage surface PG<b>1</b> is supported on the automatic reading port <b>1</b><i>a</i>. The document placement surface PG<b>2</b> is supported on the manual reading port <b>1</b><i>b</i>. The document passage surface PG<b>1</b> and the document placement surface PG<b>2</b> according to the first exemplary embodiment are formed from transparent glass.

In addition, the document guide PG<b>3</b> is supported on the upper surface of the guide support portion <b>2</b>. The document guide PG<b>3</b> according to the first exemplary embodiment is formed to extend in the front-rear direction, and is shaped to be inclined upward toward the right with the height of its left end set to be lower than the height of the upper surface of the document passage surface PG<b>1</b>. A white reference plate <b>3</b> that serves as an example of a reference member is supported on the lower surface of the guide support portion <b>2</b>. The white reference plate <b>3</b> according to the first exemplary embodiment is read as a reference for white adjustment during reading by the solid-state imaging device CCD.

As illustrated in <figref idref="DRAWINGS">FIGS. 3 and 4</figref>, a reading member <b>11</b> is disposed in a space V under the document platen PG. The reading member <b>11</b> is supported by the scanner body U<b>1</b><i>b </i>so as to be movable in the left-right direction along the lower surface of the document platen PG.

In the configuration according to the first exemplary embodiment, the first image reading position P<b>1</b> is set to the center portion of the document passage surface PG<b>1</b> in the left-right direction. In addition, an upstream position P<b>2</b> is set to the left end of the document passage surface PG<b>1</b>.

In addition, a manual reading region SE is set in advance on the document placement surface PG<b>2</b> in accordance with the largest document Gi that is placeable on the document placement surface PG<b>2</b>. A home position P<b>0</b> is set to the left end of the manual reading region SE.

The reading member <b>11</b> according to the first exemplary embodiment is supported so as to be movable between the position of the right end of the manual reading region SE and the upstream position P<b>2</b>.

In the configuration according to the first exemplary embodiment, in addition, the reading member <b>11</b> stands by at the home position P<b>0</b> before a job starts. During “automatic reading operation” for reading an image of the document Gi transported using the document transport device U<b>1</b><i>a</i>, the reading member <b>11</b> moves to the document passage surface PG<b>1</b>. During “manual reading operation” for reading an image of the document Gi manually placed on the document placement surface PG<b>2</b>, meanwhile, the reading member <b>11</b> moves from the home position P<b>0</b> to the right end of the manual reading region SE. The reading member <b>11</b> includes an irradiation system unit <b>12</b> and a reflection unit <b>13</b> disposed to the left of the irradiation system unit <b>12</b>. As illustrated in <figref idref="DRAWINGS">FIGS. 3 and 4</figref>, the irradiation system unit <b>12</b> is provided with the lamp La. An illumination light reflecting plate <b>12</b><i>a </i>is supported to the left of the lamp La. The irradiation system unit <b>12</b> also includes a reflected light reflecting plate <b>12</b><i>b </i>positioned between the lamp La and the illumination light reflecting plate <b>12</b><i>a. </i>

As illustrated in <figref idref="DRAWINGS">FIG. 3</figref>, the reflection unit <b>13</b> includes a first reflecting plate <b>13</b><i>a </i>and a second reflecting plate <b>13</b><i>b </i>disposed under the first reflecting plate <b>13</b><i>a</i>. An imaging member <b>21</b> is disposed to the right of the second reflecting plate <b>13</b><i>b</i>. An irradiation system resister sensor Sp that serves as an example of a unit position detection member is disposed in the upper left portion of the space V. The irradiation system resister sensor Sp according to the first exemplary embodiment detects the position of the reading member <b>11</b> which has been moved to the home position P<b>0</b>.

In addition, a first position sensor SN<b>1</b> that serves as an example of a first position detection member and a second position sensor SN<b>2</b> that serves as an example of a second position detection member are disposed in the upper left portion of the space V so as to correspond to a case where the reading member <b>11</b> is moved to the first image reading position P<b>1</b> or the upstream position P<b>2</b>. A third position detection sensor SN<b>3</b> is disposed in the upper right portion of the space V so as to correspond to a case where the reading member <b>11</b> is moved to the right end of the manual reading region SE.

In the first exemplary embodiment, the light-exposure optical system A is composed of the imaging member <b>21</b>, the reflected light reflecting plate <b>12</b><i>b</i>, the first reflecting plate <b>13</b><i>a</i>, and the second reflecting plate <b>13</b><i>b</i>. The solid-state imaging device CCD is disposed to the right of the imaging member <b>21</b>. The image processing section GS is disposed to the right of the solid-state imaging device CCD.

(Document Transport Device U<b>1</b><i>a</i>)

As illustrated in <figref idref="DRAWINGS">FIG. 3</figref>, the document feed tray U<b>1</b><i>a</i><b>1</b> of the document transport device U<b>1</b><i>a </i>includes a bottom portion <b>31</b> and a left wall <b>32</b> that extends upward from the left end of the bottom portion <b>31</b>. An ascent/descent plate <b>33</b> that serves as an example of an ascent/descent member is supported on the bottom portion <b>31</b> so as to be rotatable about a center of rotation <b>33</b><i>a</i>. A document loading surface <b>33</b><i>b </i>is formed on the upper surface of the ascent/descent plate <b>33</b>.

An ascent/descent rod <b>34</b> that serves as an example of an ascent/descent drive member contacts the lower surface of the left end portion of the ascent/descent plate <b>33</b>. Drive from a drive source (not illustrated) may be transmitted to a center of rotation <b>34</b><i>a </i>of the ascent/descent rod <b>34</b>. Thus, rotation of the ascent/descent rod <b>34</b> ascends and descends the left end of the ascent/descent plate <b>33</b>.

A document amount sensor <b>36</b> that serves as an example of a document amount detection member is disposed in front of the ascent/descent plate <b>33</b>. The document amount sensor <b>36</b> detects the presence or absence of the ascent/descent plate <b>33</b> or the document Gi to detect the amount of the document Gi. That is, in the case where the ascent/descent plate <b>33</b> is ascended, if the amount of the document Gi is small, the ascent/descent plate <b>33</b> is moved to a location above the height of the document amount sensor <b>36</b> so that the ascent/descent plate <b>33</b> is not detected. If the amount of the document Gi is large, on the other hand, the ascent/descent plate <b>33</b> is positioned at a location below the height of the document amount sensor <b>36</b> so that the ascent/descent plate <b>33</b> or the document Gi is detected by the document amount sensor <b>36</b>.

Hence, it is detectable whether the amount of the document is more or less than an amount set in advance on the basis of the result of detection by the document amount sensor <b>36</b> at the time when the ascent/descent plate <b>33</b> is ascended.

A nudger roller <b>37</b> that serves as an example of a document takeout member is disposed above the left end portion of the ascent/descent plate <b>33</b>. A document detection sensor <b>38</b> that serves as an example of a document detection member is disposed to the left of the nudger roller <b>37</b>. A document handling roller <b>41</b> that serves as an example of a document handling member is disposed to the left of the document detection sensor <b>38</b>.

In addition, a document transport path GH through which the document Gi is transported is formed inside the document transport portion U<b>1</b><i>a</i><b>2</b> of the document transport device U<b>1</b><i>a</i>. The document transport path GH includes a first document transport path GH<b>1</b> curved arcuately from the document handling roller <b>41</b> toward the first image reading position P<b>1</b> and a second document transport path GH<b>2</b> that extends from the first image reading position P<b>1</b> to the document paper exit tray U<b>1</b><i>a</i><b>3</b>. A document transport roller <b>43</b> that serves as an example of a document transport member is disposed in the first document transport path GH<b>1</b> at a position downstream of the document handling roller <b>41</b> in the document transport direction.

A pre-register roller <b>44</b> that serves as an example of a first correction unit which serves as an example of a correction unit is disposed downstream of the document transport roller <b>43</b>. A document register roller <b>47</b> that serves as an example of a document transport timing adjustment member is disposed downstream of the pre-register roller <b>44</b>.

As illustrated in <figref idref="DRAWINGS">FIGS. 3 and 4</figref>, a reading guide <b>51</b> that serves as an example of a reading guide member is provided in the first document transport path GH<b>1</b> at a position facing the document passage surface PG<b>1</b>. The reading guide <b>51</b> is formed in the shape of a semi-circle that projects downward. A plate support portion <b>51</b><i>a </i>is formed on the reading guide <b>51</b> at a position facing the center portion of the document passage surface PG<b>1</b> in the left-right direction.

The plate support portion <b>51</b><i>a </i>according to the first exemplary embodiment is formed to be recessed upward with respect to the reading guide <b>51</b>. The upper surface of the plate support portion <b>51</b><i>a </i>is formed to be inclined upward toward the right.

A guide reflecting plate <b>52</b> that serves as an example of a reflecting member is supported on the plate support portion <b>51</b><i>a</i>. The guide reflecting plate <b>52</b> according to the first exemplary embodiment is formed in the shape of a plate that extends in the front-rear direction. Hence, the guide reflecting plate <b>52</b> according to the first exemplary embodiment is supported so as to be inclined upward toward the right along the plate support portion <b>51</b><i>a</i>. A reading region E<b>1</b> is provided under the guide reflecting plate <b>52</b> in correspondence with the document passage surface PG<b>1</b>. The reading region E<b>1</b> according to the first exemplary embodiment extends along the sub scanning direction with respect to the document passage surface PG<b>1</b>. In the reading region E<b>1</b>, the upstream position P<b>2</b> and the first reading position P<b>1</b> correspond to the position of the upstream portion and the position of the center portion, respectively, in the document transport direction.

The guide reflecting plate <b>52</b> according to the first exemplary embodiment is supported at a position corresponding to the reflected light reflecting plate <b>12</b><i>b </i>which is supported on the reading member <b>11</b> which moves in the reading region E<b>1</b>. A guide reflecting surface <b>52</b><i>a </i>that serves as an example of a reflecting surface is provided on the lower surface of the guide reflecting plate <b>52</b>. The guide reflecting surface <b>52</b><i>a </i>according to the first exemplary embodiment is formed as a mirror surface. The guide reflecting surface <b>52</b><i>a </i>is provided to be inclined by an angle set in advance such that radiated light from the lamp La is regularly reflected toward the document passage surface PG<b>1</b>.

In addition, a transport outlet <b>53</b> is provided in the first document transport path GH<b>1</b> at a position facing the upstream portion of the reading guide <b>51</b> in the document transport direction.

A transport inlet <b>54</b> is provided in the second document transport path GH<b>2</b> at a position facing the downstream portion of the reading guide <b>51</b> in the document transport direction. A document transport roller <b>56</b> that serves as an example of a document transport member is disposed in the second document transport path GH<b>2</b> downstream of the reading guide <b>51</b> in the document transport direction.

As illustrated in <figref idref="DRAWINGS">FIG. 3</figref>, an image reading sensor <b>58</b> that serves as an example of a second reading member is disposed downstream of the document transport roller <b>56</b> at a position corresponding to a second image reading position <b>57</b> set in advance.

The image reading sensor <b>58</b> according to the first exemplary embodiment is constituted of a contact image sensor (CIS).

A reading roller <b>59</b> that serves as an example of a reading assist member is disposed downstream of the image reading sensor <b>58</b>. A document paper exit roller <b>61</b> that ejects the document Gi to the document paper exit tray U<b>1</b><i>a</i><b>3</b> is disposed downstream of the reading roller <b>59</b>.

(Function of Document Transport Device U<b>1</b><i>a</i>)

In the document transport device U<b>1</b><i>a </i>configured as described above, in the case where the document Gi is to be read, the ascent/descent plate <b>3</b> is ascended until the upper surface of the document Gi contacts the nudger roller <b>37</b> as illustrated in <figref idref="DRAWINGS">FIG. 3</figref>. Then, the nudger roller <b>37</b> is rotated to feed the document Gi. The document Gi fed by the nudger roller <b>37</b> is handled by the document handling roller <b>41</b> to be separated from the other documents. The separated document Gi is transported to the pre-register roller <b>44</b> by the document transport roller <b>43</b>. The document Gi fed by the document transport roller <b>43</b> is transported downstream by the pre-register roller <b>44</b>.

The document Gi transported by the pre-register roller <b>44</b> is transported to the first image reading position P<b>1</b> at a matching timing by the document register roller <b>47</b>. When the document Gi passes through the first image reading position P<b>1</b>, an image is read by the solid-state imaging device CCD via the light-exposure optical system A.

The document Gi having passed through the first image reading position P<b>1</b> is transported by the document transport roller <b>56</b>, and fed to the second image reading position <b>57</b>. In the case where both surfaces of the document Gi are to be read, the image reading sensor <b>58</b> reads an image on a second surface, which is opposite to a first surface read by the solid-state imaging device CCD, when the document Gi passes through the second image reading position <b>57</b>.

In the first exemplary embodiment, when an image is read by the image reading sensor <b>58</b>, the reading roller <b>59</b> presses the document Gi to stabilize the gap between the document Gi and the image reading sensor <b>58</b>. The document Gi having passed through the second image reading position <b>57</b> is ejected to the document paper exit tray U<b>1</b><i>a</i><b>3</b> by the document paper exit roller <b>61</b>.

(Control Section According to First Exemplary Embodiment)

<figref idref="DRAWINGS">FIG. 5</figref> is a block diagram illustrating the functions of the control section of the image forming device according to the first exemplary embodiment.

As illustrated in <figref idref="DRAWINGS">FIG. 5</figref>, the control section C of the copier U includes an input/output interface I/O that receives and outputs a signal from and to the outside. The control section C also includes a read-only memory (ROM) that stores a program, information, and so forth for performing a necessary process. The control section C further includes a random-access memory (RAM) that temporarily stores necessary data. The control section C additionally includes a central processing unit (CPU) that performs a process that matches the program stored in the ROM or the like. Thus, the control section C according to the first exemplary embodiment is constituted of a small information processing device, or a so-called microcomputer. Hence, the control section C may execute the program stored in the ROM or the like to implement a variety of functions.

(Signal Output Elements Connected to Control Section C of Image Preparation Section U<b>3</b>)

The control section C of the image preparation section U<b>3</b> receives output signals from signal output elements such as the operation section UI, the solid-state imaging device CCD, the image reading sensor <b>58</b>, the position sensors SN<b>1</b> to SN<b>3</b>, and the irradiation system resister sensor Sp.

The operation section UI includes the input buttons UIa used to input the number of sheets to be printed, an arrow, and so forth, the display section UIb which serves as an example of an announcement member, a copy start key UIc that serves as an example of an input member used to make an input for starting copying operation and operation for reading the document Gi, and so forth.

The solid-state imaging device CCD reads an image on the first surface of the document Gi passing through the first image reading position P<b>1</b>.

The image reading sensor <b>58</b> reads an image on the second surface of the document Gi passing through the second image reading position <b>57</b>.

The position sensors SN<b>1</b> to SN<b>3</b> and the irradiation system resister sensor Sp detect the reading member <b>11</b> which is moved to the first image reading position P<b>1</b>, the upstream position P<b>2</b>, the right end of the manual reading position SE, and the home position P<b>0</b>, respectively.

(Elements to Be Controlled Connected to Control Section C of Image Preparation Section U<b>3</b>)

The control section C of the image preparation section U<b>3</b> is connected to a principal drive source drive circuit D<b>1</b>, a transport roller drive circuit D<b>2</b>, a scan drive circuit D<b>3</b>, the power source circuit E, and the other control elements (not illustrated). The control section C outputs a control signal to the circuits D<b>1</b> to D<b>3</b>, E, and so forth.

D<b>1</b>: Principal Drive Source Drive Circuit

The principal drive source drive circuit D<b>1</b> rotationally drives the photosensitive drums Py to Pk, the intermediate transfer belt B, and so forth via a principal motor M<b>1</b> that serves as an example of a principal drive source.

D<b>2</b>: Transport Roller Drive Circuit

The transport roller drive circuit D<b>2</b> which serves as an example of a transport member drive circuit drives a transport roller motor M<b>2</b> that serves as an example of a document transport drive source to rotationally drive the document handling roller <b>41</b> and the document transport roller <b>43</b> disposed in the document transport path GH.

D<b>3</b>: Scan Drive Circuit

The scan drive circuit D<b>3</b> which serves as an example of a scanning drive circuit drives a scan motor M<b>3</b> that serves as an example of a scanning drive source to move the reading member <b>11</b> in the left-right direction along the lower surface of the document platen PG via a gear (not illustrated) or the like.

E: Power Source Circuit

The power source circuit E includes a developing power source circuit Ea, a charging power source circuit Eb, a transfer power source circuit Ec, a fixing power source circuit Ed, and so forth.

Ea: Developing Power Source Circuit

The developing power source circuit Ea applies a developing voltage to the developing rollers of the developing devices Gy to Gk.

Eb: Charging Power Source Circuit

The charging power source circuit Eb applies a charging voltage for charging the surfaces of the photosensitive drums Py to Pk to the charging rollers CRy to CRk, respectively.

Ec: Transfer Power Source Circuit

The transfer power source circuit Ec applies a transfer voltage to the second transfer roller T<b>2</b><i>b </i>via the first transfer rollers T<b>1</b><i>y </i>to T<b>1</b><i>k </i>and the contact roller T<b>2</b><i>c. </i>

Ed: Fixing Power Source Circuit

The fixing power source circuit Ed supplies power for heating a heater to the heating roller Fh of the fixing device F.

(Function of Control Section C of Image Preparation Section U<b>3</b>)

The control section C of the image preparation section U<b>3</b> has a function of executing a process that matches input signals from the signal output elements to output control signals to the control elements. That is, the control section C has the following functions.

C<b>1</b>: Image Forming Controller

An image forming controller C<b>1</b> controls drive of each member of the copier U, the voltage application timing, and so forth in accordance with the image information input from the solid-state imaging device CCD of the scanner section U<b>1</b> and the image reading sensor <b>58</b> to execute a job corresponding to image forming operation.

C<b>2</b>: Drive Source Controller

A drive source controller C<b>2</b> controls drive of the principal motor M<b>1</b> via the principal drive source drive circuit D<b>1</b> to control drive of the photosensitive drums Py to Pk etc.

C<b>3</b>: Power Source Circuit Controller

A power source circuit controller C<b>3</b> controls the power source circuits Ea to Ed to control a voltage to be applied to each member and power to be supplied to each member.

C<b>4</b>: Reading Operation Determination Unit

A reading operation determination unit C<b>4</b> determines whether reading operation to be executed is “automatic reading operation” or “manual reading operation”. The reading operation determination unit C<b>4</b> according to the first exemplary embodiment determines that “automatic reading operation” is to be executed in the case where the document Gi is detected on the document feed tray U<b>1</b><i>a</i><b>1</b> on the basis of a detection signal acquired from the document detection sensor <b>38</b> when the copy start key UIc is pressed. Meanwhile, the reading operation determination unit C<b>4</b> determines that “manual reading operation” is to be executed in the case where the document Gi is not detected on the document feed tray U<b>1</b><i>a</i><b>1</b> by the document detection sensor <b>38</b>.

C<b>5</b>: Reading Member Controller

A reading member controller C<b>5</b> that serves as an example of a movement controller includes a reading member position detection unit C<b>5</b>A and a reading member movement controller C<b>5</b>B. The reading member controller C<b>5</b> according to the first exemplary embodiment controls the reading member <b>11</b> in accordance with “automatic reading operation” or “manual reading operation” to be executed.

C<b>5</b>A: Reading Member Position Detection Unit

The reading member position detection unit C<b>5</b>A detects the position of the reading member <b>11</b>. The reading member position detection unit C<b>5</b>A according to the first exemplary embodiment detects that the reading member <b>11</b> has been moved to any of the first image reading position P<b>1</b>, the upstream position P<b>2</b>, the right end of the manual reading region SE, and the home position P<b>0</b> on the basis of detection signals acquired from the sensors SN<b>1</b>, SN<b>2</b>, SN<b>3</b>, and Sp.

C<b>5</b>B: Reading Member Movement Controller

The reading member movement controller C<b>5</b>B controls the scan motor M<b>3</b> so as to move the reading member <b>11</b> in the left-right direction along the lower surface of the document platen PG. The reading member movement controller C<b>5</b>B according to the first exemplary embodiment moves the reading member <b>11</b> to the home position P<b>0</b> when the copier U is turned on or recovers from power-saving operation.

In the case where the reading operation determination unit C<b>4</b> determines that “automatic reading operation” is to be executed, the reading member movement controller C<b>5</b>B according to the first exemplary embodiment moves the reading member <b>11</b> at the home position P<b>0</b> toward the upstream position P<b>2</b>. Then, in the case where the second position sensor SN<b>2</b> detects the reading member <b>11</b>, the reading member position detection unit C<b>5</b>A moves the reading member <b>11</b> toward the first image reading position P<b>1</b>. In the case where the first position sensor SN<b>1</b> detects the reading member <b>11</b>, movement of the reading member <b>11</b> is stopped. In the case where the job is ended, the reading member <b>11</b> is moved toward the home position P<b>0</b>. In the case where the irradiation system resister sensor Sp detects the reading member <b>11</b>, movement of the reading member <b>11</b> is stopped.

In the case where the reading operation determination unit C<b>4</b> determines that “manual reading operation” is to be executed, the reading member movement controller C<b>5</b>B according to the first exemplary embodiment moves the reading member <b>11</b> from the home position P<b>0</b> toward the right end of the manual reading region SE. Then, in the case where the third position sensor SN<b>3</b> detects the right end of the manual reading region SE, the reading member position determination unit C<b>5</b>A moves the reading member <b>11</b> toward the home position P<b>0</b>. Then, in the case where the first position sensor SN<b>1</b> detects the reading member <b>11</b>, movement of the reading member <b>11</b> is stopped.

C<b>6</b>: Lamp Controller

A lamp controller C<b>6</b> that serves as an example of a light source controller controls turning on and off of the lamp La to control radiation of radiated light. In the case where it is determined by the reading operation determination unit C<b>4</b> that “automatic reading operation” is to be executed, the lamp controller C<b>6</b> according to the first exemplary embodiment turns on the lamp La when the reading member <b>11</b> moves to the upstream position P<b>2</b>, and turns off the lamp La when the job is ended. In the case where it is determined that “manual reading operation” is to be executed, the lamp controller C<b>6</b> turns on the lamp La, and turns off the lamp La when the job is ended.

C<b>7</b>: Image Reading Unit

An image reading unit C<b>7</b> reads an image of the document Gi on the basis of an output from the solid-state imaging device CCD and the image reading sensor <b>58</b>. In the case of “automatic reading operation” and “two-sided reading” in which both the first surface and the second surface of the document Gi are to be read, the image reading unit C<b>7</b> according to the first exemplary embodiment reads the first surface and the second surface of the document Gi using the solid-state imaging device CCD and the image reading sensor <b>58</b>. In the case of “automatic reading operation” and “single-sided reading” in which the first surface of the document Gi is to be read, and in the case of “manual reading operation”, the solid-state imaging device CCD is used to read an image of the document Gi.

C<b>8</b>: Light Amount Acquisition Unit

A light amount acquisition unit C<b>8</b> includes a reference value memory C<b>8</b>A, a detected value acquisition unit C<b>8</b>B, and a tone value computation unit C<b>8</b>C, and acquires the amount of light between the first image reading position P<b>1</b> and the upstream position P<b>2</b>. The light amount acquisition unit C<b>8</b> according to the first exemplary embodiment acquires the amount of light using the solid-state imaging device CCD at a location between the first image reading position P<b>1</b> and the upstream position P<b>2</b> before the document Gi is transported through the document transport path GH in the case where the reading operation determination unit C<b>4</b> determines that “automatic reading operation” is to be executed.

C<b>8</b>A: Reference Value Memory

The reference value memory C<b>8</b>A stores, as a reference value, a detected value detected by the solid-state imaging device CCD with no document Gi, dust, or the like present between the first image reading position P<b>1</b> and the upstream position P<b>2</b>. The reference value memory C<b>8</b>A according to the first exemplary embodiment stores, as a reference value V₀, an upper limit value set in advance on the basis of the amount of light that may be received by the solid-state imaging device CCD between the first image reading position P<b>1</b> and the upstream position P<b>2</b>.

The reference value memory C<b>8</b>A according to the first exemplary embodiment stores the reference value V₀in pixels divided into meshes at intervals set in advance in the main scanning direction and the sub scanning direction in a region between the first image reading position P<b>1</b> and the upstream position P<b>2</b>.

C<b>8</b>B: Detected Value Acquisition Unit

The detected value acquisition unit C<b>8</b>B acquires a detected value detected by the solid-state imaging device CCD at a location between the first image reading position P<b>1</b> and the upstream position P<b>2</b>. The detected value acquisition unit C<b>8</b>B according to the first exemplary embodiment acquires a detected value V₁detected by the solid-state imaging device CCD at a location between the first image reading position P<b>1</b> and the upstream position P<b>2</b> before the document Gi is transported in the case where it is determined by the reading operation determination unit C<b>4</b> that “automatic reading operation” is to be executed. The detected value acquisition unit C<b>8</b>B according to the first exemplary embodiment detects the detected value V₁for each pixel for which the reference value V₀has been stored by the reference value memory C<b>8</b>A.

C<b>8</b>C: Tone Value Computation Unit

The tone value computation unit C<b>8</b>C which serves as an example of a dust determination value computation unit computes a tone value that indicates the value of light concentration at a location between the first image reading position P<b>1</b> and the upstream position P<b>2</b>. The tone value computation unit C<b>8</b>C according to the first exemplary embodiment defines the reference value V₀stored by the reference value memory C<b>8</b>A as “255”, and computes a tone value K₁that serves as an example of a dust determination value on the basis of each detected value V₁acquired by the detected value acquisition unit C<b>8</b>B. The tone value K₁according to the first exemplary embodiment is obtained by determining the integer portion of V₁/V₀×255 as K₁, and computed for each pixel as a value in 256 steps. That is, the tone value computation unit C<b>8</b>C according to the first exemplary embodiment computes the distribution of concentration in a region between the first image reading position P<b>1</b> and the upstream position P<b>2</b>. In the case where the detected value V′ is larger than the reference value V₀, the tone value K₁is set to “255” which is the upper limit value.

C<b>9</b>: Tone Threshold Memory

A tone threshold memory C<b>9</b> that serves as an example of a first threshold memory stores a tone threshold that serves as an example of a threshold for determining the presence or absence of dust. The tone threshold memory C<b>9</b> according to the first exemplary embodiment stores a detected value of light detected by the solid-state imaging device CCD as a tone threshold K_athat serves as an example of a first threshold.

In the case where the detected value of light from the guide reflecting plate <b>52</b> is normalized to 255, the detected value of reflected light is equal to or less than “210” even for plain white paper. Hence, by way of example, the tone threshold memory C<b>9</b> according to the first exemplary embodiment stores a detected value “220” obtained by adding a margin to the tone value K₁“210” for plain white paper as the tone threshold K_a.

C<b>10</b>: Size Threshold Memory

A size threshold memory C<b>10</b> that serves as an example of a second threshold memory stores a size threshold that serves as an example of a second threshold for determining, in the case where it is determined that there is dust, whether the dust is removal-target dust to be removed on the basis of the size of the dust. The size threshold memory C<b>10</b> according to the first exemplary embodiment stores a size threshold for determining whether the dust is non-removal-target dust that is relatively small such as fine dust and toner or removal-target dust that is relatively large such as large dust, a toner stain, a paper fragment, a clip, and a staple. In addition, the size threshold memory C<b>10</b> according to the first exemplary embodiment stores, as a size threshold N, the number of pixels that are continuous in the main scanning direction or the sub scanning direction set in advance and that have a detected value that is equal to or less than the tone threshold K_a.

C<b>11</b>: Foreign Matter Determination Unit

A dust determination unit C<b>11</b> includes a first dust determination unit C<b>11</b>A and a removal-target dust determination unit C<b>11</b>B, and determines on the basis of the result of reading by the solid-state imaging device CCD whether or not there is dust between the first image reading position P<b>1</b> and the upstream position P<b>2</b>. The dust determination unit C<b>11</b> according to the first exemplary embodiment determines whether or not there is dust on the basis of the detected value of reflected light from the guide reflecting plate <b>52</b> detected between the first image reading position P<b>1</b> and the upstream position P<b>2</b> before the document Gi is transported in the case where it is determined by the reading operation determination unit C<b>4</b> that “automatic reading operation” is to be executed after the copy start key UIc is pressed.

C<b>11</b>A: First Foreign Matter Determination Unit

The first dust determination unit C<b>11</b>A determines on the basis of the result of reading by the solid-state imaging device CCD whether or not there is dust between the first image reading position P<b>1</b> and the upstream position P<b>2</b>. The first dust determination unit C<b>11</b>A according to the first exemplary embodiment determines on the basis of the tone value K₁computed by the tone value computation unit C<b>8</b>C and the tone threshold K_astored by the tone threshold memory C<b>9</b> that dust is present in the case where the tone value K₁is equal to or less than the tone threshold K_a. The first dust determination unit C<b>11</b>A according to the first exemplary embodiment determines dust for each pixel between the first image reading position P<b>1</b> and the upstream position P<b>2</b>.

C<b>11</b>B: Removal-target Foreign Matter Determination Unit

The removal-target dust determination unit C<b>11</b>B which serves as an example of a second dust determination unit determines on the basis of the result of reading by the solid-state imaging device CCD whether or not there is removal-target dust between the first image reading position P<b>1</b> and the upstream position P<b>2</b>. The removal-target dust determination unit C<b>11</b>B according to the first exemplary embodiment determines that removal-target dust is present in the case where the number of pixels for which the first dust determination unit C<b>11</b>A has determined that dust is present and which are continuous in the main scanning direction or the sub scanning direction is equal to or more than the size threshold N.

<figref idref="DRAWINGS">FIG. 6</figref> illustrates an announcement screen according to the first exemplary embodiment.

C<b>12</b>: Announcement Screen Display

An announcement screen display C<b>12</b> displays, on the display section UIb, an announcement screen that announces the presence of removal-target dust in the case where it is determined that removal-target dust is present between the first image reading position P<b>1</b> and the upstream position P<b>2</b>. The announcement screen display C<b>12</b> according to the first exemplary embodiment displays, on the display section UIb, an announcement screen <b>91</b> illustrated in <figref idref="DRAWINGS">FIG. 6</figref> in the case where the removal-target dust determination unit C<b>11</b>B determines that removal-target dust is present.

C<b>13</b>: Document Transport Controller

A document transport controller C<b>13</b> controls drive of the document handling roller <b>41</b>, the document transport roller <b>43</b>, and so forth via the transport roller drive circuit D<b>2</b>.

The document transport controller C<b>13</b> according to the first exemplary embodiment drives the document handling roller <b>41</b>, the document paper exit roller <b>43</b>, and so forth in the case where the timing to transport the document Gi has come. That is, the document transport controller C<b>13</b> transports the document Gi through the document transport path GH. In the case where the removal-target dust determination unit C<b>11</b>B determines that removal-target dust is present, in addition, the document transport controller C<b>13</b> holds the document handling roller <b>41</b>, the document transport roller <b>43</b>, and so forth stationary not to start drive. That is, the document transport controller C<b>13</b> stands by without starting transport of the document Gi to the document transport path GH.

(Flow Diagram According to First Exemplary Embodiment)

Next, the flow of control in the copier U according to the first exemplary embodiment will be described with reference to a flow diagram, or a so-called flowchart.

(Flowchart of Image Reading Process)

<figref idref="DRAWINGS">FIG. 7</figref> is a flowchart illustrating an image reading process according to the first exemplary embodiment.

Processes in steps ST of the flowchart of <figref idref="DRAWINGS">FIG. 7</figref> are performed in accordance with a program stored in the control section C of the copier U. In addition, the processes are executed concurrently with other various processes of the copier U.

The flowchart illustrated in <figref idref="DRAWINGS">FIG. 7</figref> is started by turning on the copier U.

In ST<b>1</b>, it is determined whether or not a job has been started. If yes (Y), the process proceeds to ST<b>2</b>. If no (N), the process repeats ST<b>1</b>.

In ST<b>2</b>, the reading member <b>11</b> is moved toward the home position P<b>0</b>. Then, the process proceeds to ST<b>3</b>.

In ST<b>3</b>, it is determined whether or not the document detection sensor <b>38</b> has detected the document Gi. If yes (Y), the process proceeds to ST<b>4</b>. If no (N), the process proceeds to ST<b>15</b>.

In ST<b>4</b>, the reading member <b>11</b> is moved toward the upstream position P<b>2</b>. Then, the process proceeds to ST<b>5</b>.

In ST<b>5</b>, it is determined whether or not the second position sensor SN<b>2</b> has detected the reading member <b>11</b>. If yes (Y), the process proceeds to ST<b>6</b>. If no (N), the process repeats ST<b>5</b>.

In ST<b>6</b>, movement of the reading member <b>11</b> is stopped. Then, the process proceeds to ST<b>7</b>.

In ST<b>7</b>, the following processes (1) and (2) are executed, after which the process proceeds to ST<b>8</b>. <ul id="ul0001" list-style="none"><li id="ul0001-0001" num="0161">(1) The lamp La starts radiating light.</li><li id="ul0001-0002" num="0162">(2) The solid-state imaging device CCD starts reading.</li></ul>

In ST<b>8</b>, the reading member <b>11</b> is moved toward the first image reading position P<b>1</b>. Then, the process proceeds to ST<b>9</b>.

In ST<b>9</b>, it is determined whether or not the first position sensor SN<b>1</b> has detected the reading member <b>11</b>. If yes (Y), the process proceeds to ST<b>10</b>. If no (N), the process repeats ST<b>9</b>.

In ST<b>10</b>, movement of the reading member <b>11</b> is stopped. Then, the process proceeds to ST<b>11</b>.

In ST<b>11</b>, it is determined whether or not the tone value K₁is equal to or less than the tone threshold K_a. If yes (Y), the process proceeds to ST<b>12</b>. If no (N), the process proceeds to ST<b>14</b>.

In ST<b>12</b>, it is determined whether or not the number of pixels for which the tone value K₁is equal to or less than the tone threshold K_aand which are continuous in the main scanning direction or the sub scanning direction is equal to or more than the size threshold N. If yes (Y), the process proceeds to ST<b>13</b>. If no (N), the process proceeds to ST<b>14</b>.

In ST<b>13</b>, the following processes (1) to (3) are executed, after which the process returns to ST<b>1</b>. <ul id="ul0002" list-style="none"><li id="ul0002-0001" num="0169">(1) The lamp La finishes radiating light.</li><li id="ul0002-0002" num="0170">(2) The solid-state imaging device CCD finishes reading.</li><li id="ul0002-0003" num="0171">(3) The display section UIb displays the announcement screen <b>91</b>.</li></ul>

In ST<b>14</b>, automatic reading operation is executed. Then, the process returns to ST<b>1</b>.

In ST<b>15</b>, manual reading operation is executed. Then, the process returns to ST<b>1</b>.

(Effect of Document Image Reading Process)

In the copier U according to the first exemplary embodiment configured as described above, if the document Gi is not provided in the document feed tray U<b>1</b><i>a</i><b>1</b> when the copy start key UIc is pressed, “manual reading operation” is executed. If the document Gi is provided in the document feed tray U<b>1</b><i>a</i><b>1</b>, “automatic reading operation” is executed.

In the first exemplary embodiment, in the case where “automatic reading operation” is to be executed, the reading member <b>11</b> starts moving toward the first image reading position P<b>1</b> after moving to the upstream position P<b>2</b> before the document Gi is transported through the document transport path GH, that is, with the document Gi not provided on the document passage surface PG<b>1</b>.

When the reading member <b>11</b> starts moving toward the first image reading position P<b>1</b>, the lamp La is turned on to start radiating light. Then, radiated light radiated from the lamp La is reflected by the guide reflecting plate <b>52</b>, passes through the document passage surface PG<b>1</b>, and forms an image on the imaging member <b>21</b> via the reflecting plates <b>12</b><i>b</i>, <b>13</b><i>a</i>, and <b>13</b><i>b</i>, etc. to be read by the solid-state imaging device CCD. The solid-state imaging device CCD reads light reflected by the guide reflecting plate <b>52</b> while the reading member <b>11</b> is moving from the upstream position P<b>2</b> toward the first image reading position P<b>1</b>. Hence, the amount of reflected light from the guide reflecting plate <b>52</b> is read in a region between the upstream position P<b>2</b> and the first image reading position P<b>1</b>.

In the case where dust such as a paper fragment, paper powder, and dust adheres to the document passage surface PG<b>1</b> or the guide reflecting plate <b>52</b>, radiated light from the lamp La may be irregularly reflected by the dust or absorbed by the color of the dust. Thus, the amount of reflected light from the dust may be smaller than the amount of light reflected by the guide reflecting plate <b>52</b>. Hence, with the configuration according to the first exemplary embodiment, it is possible to determine that dust is present in the case where there is any tone value K₁for each pixel that is computed on the basis of the read amount of reflected light and that is equal to or less than the tone threshold K_a.

<figref idref="DRAWINGS">FIG. 8A</figref> is a graph illustrating a detected value of reflected light detected by the solid-state imaging device without the presence of dust to illustrate the effect of the first exemplary embodiment, in which the vertical axis represents the tone value and the horizontal axis represents the main scanning direction. <figref idref="DRAWINGS">FIG. 8B</figref> is a graph illustrating a detected value of reflected light detected by the solid-state imaging device with the presence of dust to illustrate the effect of the first exemplary embodiment, in which the vertical axis represents the tone value and the horizontal axis represents the main scanning direction.

Specifically, in the configuration according to the first exemplary embodiment, the tone value K₁for each pixel is computed for each line that extends in the main scanning direction in the case where “automatic reading operation” is executed. In the case where the read tone value K₁is equal to or more than “220” which is the tone threshold K_afor all the pixels as illustrated in <figref idref="DRAWINGS">FIG. 8A</figref>, it is determined that dust is not present on the line. In the case where the tone value K₁is less than “220” for some of the pixels as illustrated in <figref idref="DRAWINGS">FIG. 8B</figref>, meanwhile, it is determined that dust is present on the line.

In addition, the guide reflecting surface <b>52</b><i>a </i>is provided on the lower surface of the guide reflecting plate <b>52</b> according to the first exemplary embodiment, and radiated light radiated from the lamp La is regularly reflected by the guide reflecting surface <b>52</b><i>a</i>. Hence, a sufficient amount of reflected light to be read by the solid-state imaging device CCD is secured. In the case where a reference plate according to the related art is used, the difference between data for “white” of the reference plate and data for “white” of paper is small compared to the configuration according to the first exemplary embodiment. Thus, with the related art, the difference, or so-called contrast, between the reference plate and paper may be so small that paper may not be detected.

With the configuration according to the first exemplary embodiment, in contrast, the contrast between the reference plate and paper is large compared to the configuration according to the related art, which improves the accuracy in determining the presence or absence of dust.

In the configuration according to the first exemplary embodiment, in addition, dust is detected not only at the first image reading position but also in the reading region E<b>1</b> including the first image reading position. If dust is detected at plural locations in the sub scanning direction using a white reference plate as in the configuration according to the related art, data for “white” differ among the locations because of differences in stain on the white reference plate and distance between the white reference plate and the solid-state imaging device CCD. Hence, data for “white” are required for each location, which may increase the amount of data.

With the configuration according to the first exemplary embodiment, in contrast, light is regularly reflected by the guide reflecting surface <b>52</b><i>a </i>which is a mirror surface, and an amount of light that sufficiently exceeds the reference value V₀corresponding to the upper limit value may be received at any position in the range of the reading region E<b>1</b>.

Hence, data that serve as a criterion for determination such as data for “white” are not required for each location, which makes it possible to detect dust that is present in a region other than the first image reading position P<b>1</b> without increasing the amount of data.

If dust such as a paper fragment or a clip is present in the vicinity of the first image reading position P<b>1</b> in the case where “automatic reading operation” is executed, the document Gi being transported may be stuck to cause a jam, or the document Gi may be torn.

At the first image reading position P<b>1</b>, in particular, the gap between the reading guide <b>51</b> and the document passage surface PG<b>1</b> is narrower than that on the upstream side and the downstream side of the first image reading position P<b>1</b> in the document transport direction because of the focal length of the solid-state imaging device CCD. Thus, the gap between the reading guide <b>51</b> and the document passage surface PG<b>1</b> becomes narrower from the upstream position P<b>2</b> toward the first image reading position P<b>1</b>. Hence, if dust such as a paper fragment is present at the narrow location upstream of the first image reading position P<b>1</b> in the document transport direction, the document Gi may be easily stuck on the dust to easily cause a jam in the first document transport path GH<b>1</b>.

In the case where the dust is a large toner stain or ink stain, meanwhile, the document Gi being transported may be stained. In the case where the dust is a toner stain or large dust, and if the stain is spread or the dust moves to the first image reading position P<b>1</b>, such a stain or dust may intrude between the document passage surface PG<b>1</b> and the document Gi to cause a document image reading failure in which the stain or dust appears in the read image. That is, if dust is present upstream of the first image reading position P<b>1</b> in the document transport direction, the dust may be pushed by the document being transported to the first image reading position P<b>1</b> to appear in the image. With the configuration according to the related art in which dust is detected only on the downstream side of the image reading position in the document transport direction, such an issue may not be addressed.

With the configuration according to the first exemplary embodiment, in contrast, it is possible to detect dust in a region between the first image reading position P<b>1</b> and the upstream position P<b>2</b> on the basis of the amount of reflected light read when “automatic reading operation” is executed. When dust is detected, the document Gi is not transported. Thus, it is possible to reduce contact between the document Gi and dust compared to the configuration according to the related art in which dust is not detected in a region between the first image reading position P<b>1</b> and the upstream position P<b>2</b> when “automatic reading operation” is executed.

Thus, it is possible to reduce a jam caused with the document Gi stuck on a paper fragment, a clip, or the like and tear of the document Gi in a region with a narrow gap between the first image reading position P<b>1</b> and the upstream position P<b>2</b>, and to reduce a stain on the document Gi due to a toner stain or an ink stain.

In the scanner section U<b>1</b> according to the first exemplary embodiment, even if dust such as dust is present in a region between the first image reading position P<b>1</b> and the home position P<b>0</b>, the document Gi being transported contacts the dust, and the dust is pushed downward of the first image reading position P<b>1</b> in the document transport direction. Hence, dust hardly intrudes to the first image reading position P<b>1</b>. Hence, image reading is less adversely affected in the case where dust is present downstream of the first image reading position P<b>1</b> than in the case where dust is present upstream of the first image reading position P<b>1</b>.

In the scanner section U<b>1</b> according to the first exemplary embodiment, in addition, the second document transport path GH<b>2</b> is curved upward from a location downstream of the first image reading position P<b>1</b>. Hence, the document Gi is transported apart from the document passage surface PG<b>1</b> after passing through the first image reading position P<b>1</b>. Thus, even if a clip, a staple, or the like is present in a region between the first image reading position P<b>1</b> and the home position P<b>0</b>, an image surface of the document Gi transported through the document transport path GH<b>2</b> is less likely to be rubbed by the clip or the like to be torn. Hence, execution of “automatic reading operation” is less adversely affected in the case where dust is present downstream of the first image reading position P<b>1</b> in the document transport direction than in the case where dust is present upstream of the first image reading position P<b>1</b>.

Thus, with the configuration according to the first exemplary embodiment, it is possible to detect dust that is present upstream of the first image reading position P<b>1</b> and that easily adversely affects “automatic reading operation” compared to the configuration according to the related art in which dust is detected only downstream of the image reading position.

In addition, it is also possible to reduce spread of a stain and movement of dust to the first image reading position P<b>1</b> from the upstream side in the document transport direction along with transport of the document Gi.

Hence, it is possible to reduce an image reading failure in which a stain or dust appears in the read image, which improves the image quality of the read image. In the configuration according to the first exemplary embodiment, in particular, “automatic reading operation” is interrupted in the case where the dust is removal-target dust which is large dust for which the number of pixels that are continuous in the main scanning direction or the sub scanning direction and that have a detected value that is equal to or less than the tone threshold K_ais equal to or more than N.

In the case where the dust is fine dust or a small toner stain, it is less likely that the document Gi causes a jam. If the dust moves to the first image reading position P<b>1</b> to appear in the image, the read image may be analyzed to remove the dust through image processing according to the related art. Such image processing is known in the art, may be implemented through a variety of configurations according to the related art, and therefore is not described in detail. Hence, in the first exemplary embodiment, “automatic reading operation” is not stopped in the case where the dust is relatively small.

In the configuration according to the related art in which the size of dust is not determined, “automatic reading operation” is interrupted each time dust is detected irrespective of the size of the dust. Thus, “automatic reading operation” is interrupted even in the case where there is a low possibility that the document Gi causes a jam, which may significantly reduce the productivity.

In the scanner section U<b>1</b> according to the first exemplary embodiment, in contrast, “automatic reading operation” is interrupted in the case where the detected dust is removal-target dust which is relatively large, and “automatic reading operation” is executed in the case where the detected dust is relatively small. Thus, with the configuration according to the first exemplary embodiment, it is possible to improve the productivity by reducing the number of times when “automatic reading operation” is stopped because of dust in the case where “automatic reading operation” is executed.

In the configuration according to the first exemplary embodiment, in addition, in the case where the detected dust is removal-target dust, “automatic reading operation” is interrupted, and an error indication is displayed on the display section UIb. Specifically, it is announced, as illustrated in <figref idref="DRAWINGS">FIG. 6</figref>, that there is removal-target dust in a region between the upstream position P<b>2</b> and the first image reading position P<b>1</b>, and that the document transport device U<b>1</b><i>a </i>should be opened with respect to the document platen PG to remove the removal-target dust. Thus, the possibility that the user forgets to remove the dust is reduced compared to a case where such an announcement is not made. Thus, detected dust such as a paper fragment, a clip, a toner stain, an ink stain, and large dust is easily removed before the document Gi is transported to a region between the first image reading position P<b>1</b> and the upstream position P<b>2</b>.

(Modifications)

While an exemplary embodiment of the present invention has been described in detail above, the present invention is not limited to the exemplary embodiment, and various modifications may be made without departing from the scope and spirit of the claims. Modifications (H01) to (H016) of the present invention will be described below. <ul id="ul0003" list-style="none"><li id="ul0003-0001" num="0202">(H01) In the exemplary embodiment, the copier U is described as an example of an image forming device. However, the present invention is not limited thereto, and may be applied to a facsimile, a multi-function machine provided with functions of plural devices, and so forth. The present invention is not limited to an electrophotographic image forming device, and may also be applied to an image forming device of any image forming scheme such as printers of an inkjet recording type, a thermal head type, and a lithographic printing type. The present invention is not limited to a multi-color developing image forming device, and may also be applied to a so-called monochrome image forming device. The present invention is not limited to an image forming device of a so-called tandem type, and may also be applied to an image forming device of a rotary type or the like.</li><li id="ul0003-0002" num="0203">(H02) In the exemplary embodiment, the scanner section U<b>1</b> is described as an example of an image reading device provided in the copier U which serves as an example of an image forming device. However, the present invention is not limited thereto, and the present invention may also be applied to the scanner section U<b>1</b> alone, for example.</li><li id="ul0003-0003" num="0204">(H03) In the exemplary embodiment, it is desirably determined whether or not the detected dust is removal-target dust in the case where dust is detected in a region between the first image reading position P<b>1</b> and the upstream position P<b>2</b>. However, the present invention may also be applied to a configuration in which removal-target dust is not determined even if dust is detected, that is, a determination is made using only the tone threshold K_awithout using the number N of continuous pixels.</li><li id="ul0003-0004" num="0205">(H04) In the exemplary embodiment, dust is detected during movement from the upstream position P<b>2</b> to the first image reading position P<b>1</b>. However, the present invention is not limited thereto, and dust may be detected during movement from the first image reading position P<b>1</b> to the upstream position P<b>2</b>. In addition, the present invention is not limited to a configuration in which dust is detected between the first image reading position P<b>1</b> and the upstream position P<b>2</b>, and may also be applied to a configuration in which dust is detected between the upstream position P<b>2</b> and the home position P<b>0</b>, or between a position downstream of the home position P<b>0</b> in the document transport direction and the upstream position P<b>2</b>.</li><li id="ul0003-0005" num="0206">(H05) In the exemplary embodiment, the scanner section U<b>1</b> is capable of executing “automatic reading operation” and “manual reading operation”. However, the present invention is not limited thereto, and the movable range of the reading member <b>11</b> may be limited to a range between the home position P<b>0</b> and the upstream position P<b>2</b>, for example, so that the scanner section U<b>1</b> is capable of executing only “automatic reading operation”.</li><li id="ul0003-0006" num="0207">(H06) In the exemplary embodiment, the scanner section U<b>1</b> is capable of reading images on both surfaces of the document Gi through the solid-state imaging device CCD and the image reading sensor <b>58</b> when “manual reading operation” is executed. However, the present invention is not limited thereto, and the scanner section U<b>1</b> may be configured with the image reading sensor <b>58</b> omitted so that only the first surface of the document Gi is read through the solid-state imaging device CCD.</li><li id="ul0003-0007" num="0208">(H07) In the exemplary embodiment, the position sensors SN<b>1</b> and SN<b>2</b> are disposed in order to detect the reading member <b>11</b> which has been moved to the first image reading position P<b>1</b> and the upstream position P<b>2</b>, respectively. However, the present invention is not limited thereto. For example, movement of the reading member <b>11</b> may be controlled by determining the position of the reading member <b>11</b> on the basis of the time elapsed since the reading member <b>11</b> starts moving from the home position P<b>0</b> toward the upstream position P<b>2</b> using a timer that serves as a time measuring member and without using the position sensors SN<b>1</b> and SN<b>2</b>.</li><li id="ul0003-0008" num="0209">(H08) In the exemplary embodiment, the guide reflecting plate <b>52</b> is inclined so as to reflect radiated light from the lamp La toward the reflected light reflecting plate <b>12</b><i>b</i>. However, the present invention is not limited thereto. For example, the guide reflecting plate <b>52</b> may be inclined so as to reflect light from the illumination light reflecting plate <b>12</b><i>a </i>toward the reflected light reflecting plate <b>12</b><i>b. </i></li><li id="ul0003-0009" num="0210">(H09) In the exemplary embodiment, any light source known in the art may be used in place of the lamp La. For example, a light emitting diode (LED) light source or an organic electro luminescence (EL) light source according to the related art may also be used.</li><li id="ul0003-0010" num="0211">(H010) In the exemplary embodiment, the light-exposure optical system A is composed of the imaging member <b>21</b>, the reflected light reflecting plate <b>12</b><i>b</i>, the first reflecting plate <b>13</b><i>a</i>, and the second reflecting plate <b>13</b><i>b</i>. However, the present invention is not limited thereto, and any configuration known in the art may also be adopted. For example, a reflection unit of any configuration that differs from the reflection unit <b>13</b> in number or shape of reflecting members to be used may also be adopted. That is, in the first exemplary embodiment, the guide reflecting plate <b>52</b> indirectly reflects light toward the solid-state imaging device CCD via the light-exposure optical system A. However, the guide reflecting plate <b>52</b> may directly reflect light toward the solid-state imaging device CCD.</li><li id="ul0003-0011" num="0212">(H011) In the exemplary embodiment, the number N of pixels that are continuous in the main scanning direction or the sub scanning direction and that have a detected value that is equal to or less than the tone threshold K_ais stored as the size threshold which serves as an example of a second threshold. However, the present invention is not limited thereto. For example, a region of pixels of N (pixels)×N (pixels), N×M, or the like that are continuous in the main scanning direction and the sub scanning direction and that have a detected value that is equal to or less than the tone threshold K_amay also be stored as the size threshold. The numbers N and M of pixels may be changed to any value in accordance with the design, specifications, or the like.</li><li id="ul0003-0012" num="0213">(H012) In the exemplary embodiment, the reflected light detected value “220” is stored as the tone threshold K_awhich serves as an example of a threshold for determining the presence of absence of dust. However, the present invention is not limited thereto, and the tone threshold may be changed to any value in accordance with the design, specifications, or the like.</li><li id="ul0003-0013" num="0214">(H013) In the exemplary embodiment, the guide reflecting surface <b>52</b> is desirably provided with the guide reflecting surface <b>52</b><i>a </i>which serves as an example of a reflecting surface that regularly reflects radiated light from the lamp La. However, the present invention is not limited thereto, and the guide reflecting plate <b>52</b> may be installed at an angle that is different from the angle for regular reflection if a sufficient amount of light may be secured.</li><li id="ul0003-0014" num="0215">(H014) In the exemplary embodiment, the guide reflecting surface <b>52</b><i>a </i>is described as an example of a reflecting surface with a difference from the amount of light reflected from the document Gi is larger than the difference in amount of light set in advance. However, the present invention is not limited thereto. For example, the guide reflecting surface <b>52</b><i>a </i>may be colored in black or the like to increase the difference from the amount of light reflected from the document Gi. Besides, a specific image that enables detection of a blockage by dust such as a paper fragment, e.g. an image in which minute dots that are invisible to human eyes, or so-called stealth dots, are distributed irregularly, may be formed on the reflecting surface.</li><li id="ul0003-0015" num="0216">(H015) In the exemplary embodiment, dust is detected in the reading region E<b>1</b> which is located between the first image reading position P<b>1</b> and the upstream position P<b>2</b> in the document transport direction. However, the present invention is not limited thereto. For example, dust may be detected at a position that is set downstream of the first image reading position P<b>1</b> in the sub scanning direction and that is different from the first image reading position P<b>1</b>, and dust may also be detected in a region including the first image reading position P<b>1</b> and set upstream and downstream of the first image reading position P<b>1</b> in the sub scanning direction.</li><li id="ul0003-0016" num="0217">(H016) In the exemplary embodiment, dust is detected in the entire reading region E<b>1</b>. However, the present invention is not limited thereto. For example, dust may also be detected at two or more plural positions at intervals set in advance.</li></ul>

The foregoing description of the exemplary embodiment of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiment was chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.